Info

Various acids promote the substitution reaction of 1-hydroxyindoles, 1-hy-droxytryptamines, and 1-hydroxytryptophans with nucleophiles. We have demonstrated that pKa of the organic acids has a remarkable effect on the reaction employing 1-hydroxy-Nb-methoxycarbonyltryptamine (52) as a substrate [33]. As can be seen from Table 5, neither propionic nor acetic acids have sufficient acidity for inducing the substitution reaction. They yield a slight quantity of dehydroxylated tryptamine (55) (entries 1-2). As the acidity increases, the yield of 5-hydroxytryptamine (104a), a product of nucleo-

Table 5 Effect of an acid on the reaction of Nb-methoxycarbonyl-1-hydroxytryptamine

NHCOOMe

Table 5 Effect of an acid on the reaction of Nb-methoxycarbonyl-1-hydroxytryptamine